The development and commercialization of extracellular matrix for use in cartilage repair will be of major benefit to the quality of life and to the economics of health care worldwide. The long term objective of this Phase II proposal is to develop a polymer matrix that supports the in situ migration of chondrogenic progenitor stem cells capable of repairing articular cartilage defects. A method of fabricating collagen-proteoglycan matrices was developed in Phase I of the project and the resulting matrices were reported to support both osteogenesis and chondrogenesis. Based on their earlier success, the investigators plan to optimize and refine their collagen based matrices in the Phase II study. Injectible or arthroscopically implantable matrix or matrix impregnated with chondrogenic growth factor will be tested for its ability to integrate with host tissue in cow and sheep cartilage explant cultures. These matrices will also be evaluated using four in vivo animal models (rat, rabbit, dog and horse). The investigators plan to assess implantation of the matrix by athroscopy and to analyze the mechanical properties of the repair tissue. Availability of biocompatible matrices that would facilitate migration and differentiation of autologous progenitor cells stem cells into functional chondrocytes provides a novel, cost-effective technique for restoration and repair of damaged cartilage tissue. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE